While preamp distortion creates the square wave, power section distortion creates feel . When the power tubes (EL34s, 6L6s, or EL84s) are overdriven, they sag. The voltage drops and recovers with the attack of the note. This creates "bloom"—a sensation where the note swells slightly after the pick attack.
In the acoustic world, dynamics are simple: hit a string harder, get a louder note. The electric guitar, however, becomes a paradox when overdriven. The harder you play, the less the volume increases. Instead, the tone changes. Overdriven Guitar Dwp